Jeju-do

Jeju province encompasses the South Korean island of Jeju in the Korea Strait. It's known for its beach resorts and volcanic landscape of craters and cavelike lava tubes. Hallasan Mountain, a dormant volcano, features hiking trails, a crater lake at the 1,950m summit and nearby Gwaneumsa Temple. The Geomunoreum Lava Tube System includes 7km-long Manjanggul Cave, created centuries ago when Hallasan was still active.